TCL 65S517 No Backlight, Picture and Sound OK

[budm]

Re: TCL 65S517 No Backlight, Picture and Sound OK

What Voltage do you get on pin 5 and 6 of TS3, and pin 1 and pin 16 of the OZ IC with ref to GND?

[Diah]

Re: TCL 65S517 No Backlight, Picture and Sound OK

yes its really mysterious you have 0V on LED.. but after take look on this Roku TV, it had option of LED clarity. it sound to me the signal Back light ON which the Main boards send to PSU are include Digital Code or Freq of signal.

i would suggest to disconnected the main boards totally from the PSU, and run the PSU as Standalone and turn on the BL as well Power on...

[rebelkustoms]

Re: TCL 65S517 No Backlight, Picture and Sound OK

What Voltage do you get on pin 5 and 6 of TS3, and pin 1 and pin 16 of the OZ IC with ref to GND?

Hi Budm, I get -35 mv on pins 5 and 6 of TS3, I included a diagram of what every pin is reading on the OZ IC next to its diagram

[budm]

Re: TCL 65S517 No Backlight, Picture and Sound OK

So there is no activity at those pins of TS3.
The confusing part is that the application circuit pinout does not match the actual part, I.E. the VCC pin, the ENA pin 13, etc. but at least the GND pin and the transformer driver pins do match.

So does the the Voltage on pin 4 (ENA per RJ) change state when TV is OFF and when TV is turned ON?

[rebelkustoms]

Re: TCL 65S517 No Backlight, Picture and Sound OK

yes its really mysterious you have 0V on LED.. but after take look on this Roku TV, it had option of LED clarity. it sound to me the signal Back light ON which the Main boards send to PSU are include Digital Code or Freq of signal.

i would suggest to disconnected the main boards totally from the PSU, and run the PSU as Standalone and turn on the BL as well Power on...

So with main board disconnected and the set on, here are the readings I get. When you say turn on the BL are you talking about placing voltage to it in some way to get it turn on backlights?

[rebelkustoms]

Re: TCL 65S517 No Backlight, Picture and Sound OK

So there is no activity at those pins of TS3.
The confusing part is that the application circuit pinout does not match the actual part, I.E. the VCC pin, the ENA pin 13, etc. but at least the GND pin and the transformer driver pins do match.

So does the the Voltage on pin 4 (ENA per RJ) change state when TV is OFF and when TV is turned ON?

SO as far as TS3 goes, pins 5 and 6 are 0v when off and go to -36mv when the set is turned on.

Pin 4 (being 4th pin down the left side in the pic) goes from 0v off to 3.2 mv when ON.

Pin 13 (being 4th pin down on the right side of the IC in the pic) goes from 6mv OFF to -35mv on.

Could this thing be diagramed upside down or something?

[budm]

Re: TCL 65S517 No Backlight, Picture and Sound OK

I think I found the correct pin out for OZ9976AGN

So pin 4 is ENA (BL-ON), so do you mean 3.2V, not 3.2mV when TV is on, correct?

The IC has VCC, ENA, PWM control all present but it still does not drive the TS3 transformer.

[rebelkustoms]

Re: TCL 65S517 No Backlight, Picture and Sound OK

I think I found the correct pin out for OZ9976AGN

So pin 4 is ENA (BL-ON), so do you mean 3.2V, not 3.2mV when TV is on, correct?

The IC has VCC, ENA, PWM control all present but it still does not drive the TS3 transformer.

Yes your schematic makes more sense. Mine was right from O2 Micro datasheet idk whats with it.

Yes pin4 (as per your schematic) gets 3.2V with the set on.

At TS3 it gets a few mv while off and goes to -35mv when turned on.

Does signal/Voltage travel through TS2 and QW3/4 to get to TS3 or the opposite? I dont know much about circuit flow I am just looking at the physical pathways.

[rebelkustoms]

Re: TCL 65S517 No Backlight, Picture and Sound OK

I suspect there must be something FATAL in these Power Supplys. This was a costco model set manufactured in feb 2019 and there are 0 replacements PS's for sale out there. All out of stock.

[Diah]

Re: TCL 65S517 No Backlight, Picture and Sound OK

So with main board disconnected and the set on, here are the readings I get. When you say turn on the BL are you talking about placing voltage to it in some way to get it turn on backlights?

if this V. reading you listed after you turn on the PSU as standalone. ( mean the connected pins STB--> power On, STB--->BL-ON ) then you have much issue at LED BL or burned socket / connection at BL

[Spitz]

Re: TCL 65S517 No Backlight, Picture and Sound OK

I suspect there must be something FATAL in these Power Supplys. This was a costco model set manufactured in feb 2019 and there are 0 replacements PS's for sale out there. All out of stock.

Check Ebay and use 40-L141W4-PWC1CG as the part number.

[rebelkustoms]

Re: TCL 65S517 No Backlight, Picture and Sound OK

Check Ebay and use 40-L141W4-PWC1CG as the part number.

That one looks very similar and is only 1 number off but piece by piece it has a few differing components on it which make me wonder if it will work.

[rebelkustoms]

Re: TCL 65S517 No Backlight, Picture and Sound OK

if this V. reading you listed after you turn on the PSU as standalone. ( mean the connected pins STB--> power On, STB--->BL-ON ) then you have much issue at LED BL or burned socket / connection at BL

When the Main Board is Unplugged from PSU I get 0v or 2mv at Main Board power on pin and 0v or 2mv at BL-ON pin.

With Main Board CONNECTED I get 2.3v at power on pin and 3.2 at BL-ON pin.

[Diah]

Re: TCL 65S517 No Backlight, Picture and Sound OK

When the Main Board is Unplugged from PSU I get 0v or 2mv at Main Board power on pin and 0v or 2mv at BL-ON pin.

With Main Board CONNECTED I get 2.3v at power on pin and 3.2 at BL-ON pin.

that's correct how it should be... BUT running PSU as Standalone ( Main boards unplugged ) you will have on sockets which it goes to MB only about 3.3V at pins stand by. this stand by pins if we jumper it to Power On and to BL-ON. thr PSU will run stand alone with out MB.. at this points you can measure Voltage on BL sockets in case the BL didn't come ON

BTW. was essential from those who are diving with diagram and high level diagram tracing to explain OP with thei mother language how to run PSU stand alone.

[rebelkustoms]

Re: TCL 65S517 No Backlight, Picture and Sound OK

Hey Budm,
I think Diah above is trying to explain how to "turn on" the PSU with the motherboard disconnected but he is having a hard time getting it across in english. are there other pins I can jump to PWR_ON and BL_ON to get the PSU to turn on, or is their a guide or video that can help me.

[nomoresonys]

Re: TCL 65S517 No Backlight, Picture and Sound OK

What's going on with C412, C431 and C432? They look ill, what's on the top of them? If that's leakage then they are shot.

[rebelkustoms]

Re: TCL 65S517 No Backlight, Picture and Sound OK

What's going on with C412, C431 and C432? They look ill, what's on the top of them? If that's leakage then they are shot.

Those are all fine. Must be a bad pic. Just for fun I desoldered and checked them all with my ESR and they are all 3 good.

[rebelkustoms]

Re: TCL 65S517 No Backlight, Picture and Sound OK

So I kinda ran out of things to test on this thing so I was visually combing over the board. Paying attention to the area around the OZ 16 pin IC. I was testing these 330 resistors and they are testing around 7.8 Ohms which from what I understand is pretty off.
Then I saw this surface mount cap next to them right near the IC and it looks like it is leaking black. It took FOREVER to get a good pic but I think you can spot it here. Let me know what you think. There looks to be some corrosion nearby too.

[vinceroger69]

Re: TCL 65S517 No Backlight, Picture and Sound OK

i would certainly change that smd capacitor (certainly discolored etc) you should be able too remove and measure one of the other ones so you can get a replacement

[budm]

Re: TCL 65S517 No Backlight, Picture and Sound OK

Can you take resistance reading of each pin of the IC with ref to Ground for me?